Opinion by: Paul W. Green, Justice.

This is a wrongful death and survival action. Appellant Maria M. Martinez sued appellee Browder Lee Graves for damages when her son, Gabriel Adrian Gonzalez, was killed in a collision between Gonzalez's four-wheel all-terrain vehicle (ATV) and a pickup truck driven by Graves. Following a trial, the jury found Gonzalez and Graves equally responsible for the accident. The jury awarded zero damages to Martinez on her wrongful death claim and $6894.33 damages on the survival claim. Martinez appeals, claiming the jury awards were against the great weight and preponderance of the evidence. Graves asserts seven issues on cross-appeal in the event this Court sustains Martinez's appeal. We reverse and remand.

Standard of Review

Both sides agree that Martinez's complaints concerning the jury awards are properly reviewed according to the traditional factual sufficiency standard. See Pool v. Ford Motor Co., 715 S.W.2d 629, 634-36 (Tex. 1986); Cain v. Bain, 709 S.W.2d 175, 176 (Tex. 1986). Under this standard, "the court of appeals must consider and weigh all the evidence, and should set aside the verdict only if it is so contrary to the overwhelming weight of the evidence as to be clearly wrong and unjust." Id.

Background

On a clear, dry Saturday at approximately 9:40 a.m., Browder Lee Graves was driving his pickup truck at about 30 miles per hour in a northerly direction on Magnolia Street in Uvalde, Texas. At the same time, nineteen year old Gabriel Adrian Gonzalez was driving his ATV westbound through an alley that intersected Magnolia Street. Nearby, Marie Horner, a retired school teacher, was outside having coffee with her son Jay who was in town visiting. Both Marie and Jay heard Gonzalez's ATV noisily coming down the alley behind Marie's home at a high rate of speed. They looked at the ATV as it passed and Jay estimated its speed at 40 miles per hour. The driver was not wearing a helmet. Marie's home is the second house from the end of the alley, and neither she nor Jay thought the ATV driver made any attempt to slow down as he neared Magnolia Street. Almost immediately after the ATV left their view they heard a crash. Gonzalez's ATV had exited the alley into the path of Graves's pickup truck. Jay immediately went to the scene of the collision and saw that Gonzalez was not conscious and did not appear to be in pain. Gonzalez was airlifted to a hospital in San Antonio where he died two hours after the accident.

Discussion

Martinez argues the zero damages finding on her wrongful death claim is against the great weight and preponderance of the evidence because the evidence showed that she and Gonzalez had a close relationship and that a mother's loss of a son implicates a significant compensable injury. See Sanchez v. Schindler, 651 S.W.2d 249, 252 (Tex. 1983) ("injuries to the familial relationship are significant injuries and are worthy of compensation"). The damage question submitted to the jury included elements for pecuniary loss, loss of companionship and society, and mental anguish. We begin by summarizing all the evidence relevant to these elements of damages.

Martinez lives in La Pryor, Texas where she is employed as a cook. Gonzalez, one of her thirteen children, dropped out of school at age sixteen and moved to Uvalde to work. He was a "so-so, reluctant worker." Although he lived twenty miles away, Gonzalez would visit his mother two or three times a month. He sometimes gave his mother $10 or $20, but he would also borrow money from her. He sometimes helped around his mother's house, cleaning the yard, raking the leaves and throwing out the trash. Gonzalez told his mother he wanted to be truck driver and wanted to buy her a car and build her a house. However, she knew nothing of the kind of work Gonzalez did, what his income was, or what property he had. Although Martinez knew Gonzalez had a girlfriend, she did not know her name. Martinez had not seen Gonzalez for a couple of months before his death. When she found out about his death, she felt empty and cried a lot. She took off from work for two weeks after Gonzalez's death and when back at work she sometimes cried. Martinez lost much of her appetite after Gonzalez's death and had difficulty sleeping. She still regularly visits Gonzalez's grave two years after the accident.

"The mental processes by which a jury determines the amount of damages is [sic] ordinarily not cognizable by an appellate court and where the law furnishes no precise legal measure for the recovery of damages, the amount to be awarded is largely discretionary with the jury." Terry v. Garcia, 800 S.W.2d 854, 859 (Tex.App.-San Antonio 1990, writ denied). Indeed, a reviewing court is not authorized to substitute its judgment for that of the jury. Marvelli v. Alston, 100 S.W.3d 460, 482 (Tex.App.-Ft. Worth 2003, pet. filed). But a finding of zero damages in the face of clear injury may be set aside by an appellate court as being against the great weight and preponderance of the evidence. See Cornelison v. Aggregate Haulers, Inc., 777 S.W.2d 542, 547-48 (Tex.App.-Fort Worth 1989, writ denied).

Because the jury failed to find any damages under the global wrongful death damages question, we must determine whether or not the jury's answer is against the great weight of the evidence on each of the elements listed. We begin with the elements of pecuniary loss and the loss of companionship and society.

The jury heard evidence that Gonzalez left home three years before he died and only returned occasionally to visit his mother. Martinez knew little if any about Gonzalez's life in Uvalde, and his periodic small donations of money to her were offset by the money Gonzalez sometimes borrowed from her. In short, there is little evidence to show Gonzalez financially supported his mother and the jury was entitled to believe that he did not. In addition, although the record contains some evidence that Gonzalez provided his mother with some degree of care and attention, it was little enough that the jury was entitled to believe Gonzalez's death would not deprive his mother of blessings he did not offer her in life.

The mental anguish element of damage is viewed from a different perspective than the other elements. This element is measured not from what Martinez may have lost as a result of her son's death, but what his death may have caused her to experience as a mother. Martinez's testimony exhibits what virtually any mother would experience as a result of her child's death: emotional pain, torment, and suffering. Indeed, in the absence of evidence of estrangement, it would be difficult to imagine that mental anguish is not associated with any parent's loss of a child. As recognized by the Supreme Court in Sanchez, the familial bond is quite strong and any loss to that relationship is significant. See Sanchez, 651 S.W.2d at 252.

Graves suggests, however, that the evidence of Gonzalez's absence from home and his infrequent visits with his mother supports the jury's zero damages answer on the mental anguish element. But absence from home, by itself, does not weaken the familial bond. Neither would the reason for the absence generally make any difference-whether the child is away from home raising a family, working, serving in the military, or even confined in a penitentiary, a mother's love and affection for her child can remain just as strong and enduring.

Martinez testified that her son's death caused loss of appetite, difficulty sleeping, and crying bouts at work. She also testified that she feels empty because of the loss of her son and continues to visit his grave. This evidence is wholly consistent with the manifestation of a mother's grief and greatly outweighs any evidence inferring that Martinez's relationship with her son was severed to the extent that she was not emotionally damaged by his death, including the contention that the jury did not believe Martinez's testimony.

For these reasons, we hold that the jury's verdict of "zero" on the mental anguish element of the wrongful death damages is against the great weight and preponderance of the evidence and is manifestly unjust. Because this holding requires remand for a new trial, it is unnecessary to address Martinez's remaining complaint. In light of our ruling on Martinez's appeal, we must now address Graves's cross-appeal issues.

Cross-Appeal

Graves asserts seven issues in his cross appeal, each complaining of the trial court's exclusion of evidence showing the presence of cocaine in Gonzalez's blood stream at the time of his death. In issues one, two, three, and six, Graves asserts the trial court erred in excluding the testimony of Dr. James C. Garriott, his toxicologist. In issue five, Graves contends the court erred in excluding the testimony of Dr. Vincent Papa, Martinez's rebuttal expert. In issue four, Graves contends the trial court erred in excluding the testimony of Katherine Diana who was the custodian of records for the Bexar County Medical Examiner's Office. Finally, in issue seven, Graves asserts the trial court erred in excluding the lab results of Gonzalez's toxicology screen. Because all seven issues address the exclusion of expert evidence regarding the presence of cocaine in Gonzalez's system, we address these issues together.

We review a trial court's exclusion of expert testimony for abuse of discretion. Gammill v. Jack Williams Chevrolet, 972 S.W.2d 713, 718-19 (Tex. 1998); E.I. du Pont de Nemours Co., Inc. v. Robinson, 923 S.W.2d 549, 558 (Tex. 1995); Martinez v. City of San Antonio, 40 S.W.3d 587, 592 (Tex.App.-San Antonio 2001, pet. denied). A trial court abuses its discretion when its ruling is arbitrary, unreasonable or without reference to any guiding rules or legal principles. Robinson, 923 S.W.2d at 558.

Admissibility of expert testimony is governed by the Texas Rules of Evidence and the Robinson factors. Tex. R. Ev. 701, 702, 705(c); Robinson, 923 S.W.2d at 556; Martinez, 40 S.W.3d at 592. Under Robinson, the expert's testimony must be both relevant to the issues and based on a reliable foundation. Robinson, 923 S.W.2d at 556; Martinez, 40 S.W.3d at 592. In addition to being relevant and reliable, under the rules of evidence, the probative value of expert testimony must not be outweighed by the danger of unfair prejudice which may result from its admission. Tex. R. Ev. 403, 702; Robinson, 923 S.W.2d at 557. In order to be considered relevant, expert testimony must bear a relationship to the issue in the case such that the testimony will aid the jury. Gammill, 972 S.W.2d at 720. To be reliable, the scientific evidence must be grounded in scientific method and procedure such that it amounts to more than subjective belief or unsupported speculation. Id.

The Texas Supreme Court has enumerated a list of factors to be used in determining the reliability of expert testimony: (1) the extent to which the theory has been tested; (2) the extent to which the technique relies upon the subjective interpretation of the expert; (3) whether the theory has been subjected to peer review and/or publication; (4) the technique's potential rate of error; (5) whether the underlying theory or technique has been generally accepted as valid by the relevant scientific community; and (6) the non-judicial uses which have been made of the theory. Robinson, 923 S.W.2d at 557. These factors, however, do not always apply to expert testimony, because they do not always fit. Gammill, 972 S.W.2d at 726. In some instances, the expert's skill and experience may support a finding that his testimony is reliable and relevant. Id. In cases like this, the trial court may consider whether there is too great of an analytical gap between the data and the expert's opinion. Id. at 727.

At trial, Graves presented the testimony of Drs. Garriott and Papa, as well as that of Katherine Diana, as an offer of proof. Toxicologist Dr. James Garriott testified that he was the chief toxicologist and director of the toxicology lab for the Bexar County Medical Examiner's Office from 1982 until 1997 and that he had personal knowledge of the procedures, methods, and equipment used by this office. He also testified as to the autopsy procedures utilized at the Medical Examiner's office and stated that the national forensic guidelines used by the lab are generally set forth by the American Board of Forensic Toxicology and are accepted by the forensic toxicological community as reliable. Dr. Garriott further testified that he was familiar with the toxicology tests run on Gonzalez, the results of which are generally considered reliable. Dr. Garriott also testified that, looking at the tests conducted on Gonzalez's body, he was of the opinion that cocaine was present in his blood, urine, and brain at the time of his accident and at the time of his death. Finally, Dr. Garriott testified as to the effects of cocaine on the body, including euphoria, hyperactivity, aggressiveness, and some high-risk taking as possible effects of the drug. He stated these effects to have been established though scientific studies which have been published and generally accepted in the scientific community. He also stated that Gonzalez's actions at the time of the accident may have been consistent with these effects.

Dr. Vincent Papa, a pathologist designated as a rebuttal witness to Dr. Garriott, testified as to the process used during an autopsy to screen for the presence of drugs in the blood and urine of an individual such as Gonzalez. He asserted that the processes used were commonly accepted by the toxicology community as being reliable. He also testified that there was no question that Gonzalez had cocaine present in his urine at both the time of his accident and the time of his death, two hours later, but that he was not able to tell when Gonzalez had ingested the cocaine without making a number of assumptions concerning the amount of cocaine ingested and Gonzalez's metabolic rate.

Bexar County Medical Examiner's Office records custodian Katherine Diana's written questions and answers indicated that records such as the lab report which contained the results of the toxicology screen were kept in the regular course of business.

In his brief, Graves argues the court should not have excluded the testimony and lab report because this evidence is relevant, reliable, and its probative value is not outweighed by the prejudicial effect it may have had on the jury. In addition, Graves points to § 724.063 of the Texas Transportation Code which states that evidence of the presence of a controlled substance is admissible in a civil action.

Even assuming the evidence presented was both relevant and reliable under Robinson, the trial court is still afforded discretion in deciding whether the probative value of the evidence is outweighed by its prejudicial effect. Robinson, 923 S.W.2d at 557. Looking at the evidence as presented to the trial court, none of the excluded witnesses or evidence were able to establish the amount of cocaine ingested by Gonzalez or the time at which he ingested the drug or draw a definite correlation between his specific reaction to the drug in his system and the accident. The trial court may have found the probative value of this testimony to be outweighed by the possible prejudicial effect it may have had on the jury. For that reason, we affirm the judgment of the trial court as to the exclusion of the testimony and the lab report.

We reverse the trial court's verdict and remand the case for further proceedings consistent with this Court's decision.